Channel bending machine



July 31, 1934. D. c. BAILEY CHANNEL BENDING MACHINE 2 Sheets-Sheet 1 Filed July 29, 1932 I July 31, 1934. c BAlLEY I 1,968,010

CHANNEL BENDING MACHINE Filed July 29, 1932 2 Sheets-Sheet 2 Patented July 31, 1934 UNITED STATES PATENT OFFlCE CHANNEL BENDING MACHINE David C. Bailey, Amesbury,-Mass.

Application July 29, 1932, Serial No. 625,904 5 Claims. (01. 153-32) This invention relates to machines for bending metal in strip form, and more particularly when the strip is of thin metal and has been bent into channel form.

It is common practice, in bending metal strips of this character, to wrap or 'convolute the strip about a form of suitable shape under tension, and, when this has been done by power driven mechanism, the strip has been secured at one end to the form about which it is to be bent, and it has been held at-the opposite end by a frictional clamp, through which the strip is drawn when the form and clamp are moved relatively to perform the bending operation, so that the strip may be kept under tension, and a suflicient length of the strip may be given off to correspond to the amount taken up by bending the same about the form.

Machines of this character are objectionable for the reason that it is difficult to gage properly the force of frictional engagement necessary to insure the desired degree of tension required by the bending operation, for, if the clamp is engaged with the strip with too strong a frictional force, the strip is likely to be ruptured, while if this force is too weak the bending operation would not be satisfactorily performed. Moreover, strips of this character are frequently employed for finishing, or ornamental purposes and consequently have a finished surface which is likely to be scratched, or marred by any relative movement of the holding means thereon; such as the frictional clamping means above referred to.

In the production of these ornamental finish strips, it is frequently desirable to form a plural-- ity of bends in the strip, and a substantial saving in labor costs may be made by forming the necessary bends in each strip by a single operation.

The objects of my invention are to provide a machine for bending metal channel strips, or the like, of the character above referred to, with which the bending operation may be performed without in any way marring the finished surface of the strip, which will perform the bending operation at a plurality of points in the strip, and which will enable the entire operation to be rapidly performed by power driven means.

I accomplish these objects primarily by providing opposing clamping means for opposite portions of the strip to be bent, each adapted to hold the strip against relative movement therein and by relatively moving one or both of said clamps with relation to-a bending form in a manner both to perform the bending operation and to place the strip under the necessary longitudinal tension while this operation is being performed, without permitting any movement of the strip in either of the clamps.

For a more detailed description of a preferred embodiment of the invention, reference is made to the following specification, in connection with the accompanying drawings, in which:-

Fig. 1 is a top plan view of a machine embodying my invention.

Fig. 2 is a sectional view at line 22 of Fig. 1.

Fig. 3 is a detail sectional view at line 3-3 of Fig. 1.

Fig. 4 is a front elevation of the machine.

Figs. 5 and 6 are views of the material operated before and after bending respectively.

As shown in the drawings, the frame 10 on which the machine is mounted, is in the form of an ordinary table supported at a convenient height for the operator. A bending form 12 is mounted horizontally on the middle portion of the table and is securely held in a fixed position. It will be understood that the particular form shown is merely illustrative, and may be varied' within certain limits according to the character of the work to be performed, which, in the present instance, is shown as adapted to bend a straight strip a: of thin metal in channel form, as shown in Fig. 5, into the U-form :2 shown in Fig. 6. To this end the edge 13 of the form 12 is rounded transversely and shaped to flt into the strip, and is convexly curved longitudinally throughout the greater portion of its length, each end portion thereof being curved sharply through an arc of approximately 90.

The machine shown is designed to be power 19, are mounted vertically in the frame and each is provided with a bevel gear 20 at its lower end arranged in mesh with the gears 18. A pair of gear segments 21 are mounted on vertical pivot shafts 22 and are arranged in mesh with gears 23 on the upper endsof shafts 19, so that, when shaft 14 is driven forwardly, the segments 21 will be swung horizontally in the direction of the arrows in Fig. 1.

A pair of g'uideways 24 are mounted on the top sides of each segment 21 and a slide 25 is mounted ll? in each pair of guideways 24. A clamp is mounted on the top side of each slide 25, which comprises a fixed member 26, which is shaped to fit .into the channel strip 0:, as shown in Fig. 3, and a movable member 27,- which is shown as a simple screw having a handle,'althoug-h, in practice a much more powerful clamping device is employed which enables the strip at to be so firmly clamped that any movement of the strip in the clamp is prevented. Each clamp member is of sufficient length to engage the end portions of the strip :1: throughout a considerable portion of the length thereof. A stud 28 is mounted in each slide 25, and an arm 29 is pivotally mounted at its middle on said stud. A pair of friction rolls 30 are mounted one in each end of each arm 29, and each pair of rolls are arranged for engagement with the surfaces of a pair of fixed cams 32, which extend horizontally through approximately 90 from the front of the machine rearwardly, the cams 32 being extended in convergent relation, and each cam having a recessed portion 33, 34 at each end thereof. A spring 35 normally holds each slide 25 in initial position, in which a shoulder on the slide engages one end of the guideways 24. A stop gage 36 is mounted on each slide for engaging the ends of the strip a: when placed in position in the clamps, so that the position of the strip therein may be accurately determined. The strips, in practice, are usually cut to a uniform length.

The initial position of the parts is shown in full lines in Figs. 1 and 2 and, when the channel strip is clamped in position in the machine, as shown, it will be held at a short distance from the edge 13 of the form 12. In this position also, the front rolls 30 will be held in the cam recesses 33.

Assuming that the strip has been securely clamped in position at both ends, the machine is set in operation, causing the gear segments 21 to be swung on their pivots in the direction of the arrows in Fig. 1. By this movement the clamps and the slide 25 are carried, or swung rearwardly, causing the front rolls 30, to be carried out of the recesses 33 onto the higher parts of the camsp32. By this action the shafts of the rear rolls 30 act as pivots for the arms 29, so that the slides 25 are pulled outwardly, or away from each other and the clamps are separated to a sufficient extent to place a strong initial tension on the strip. At the same time the strip will be carried bodily rearward, so that it will pass onto the middle of the edge portion of the form 12. The swinging motion of the clamps and slides will then be continued, so that the opposite portions of the strip will be bent or convoluted about the front edge of the form 12, and then about the more. sharply curved end portions thereof, until the clamps and the other parts carried by the segments 21 are moved into a the dotted line positions of Fig. 1.

It will be apparent that, as the strip, is con-,

voluted about the convex edge of the formfthe straight line distance from the middle of the strip to its ends will be shortened, or the strip may be considered as being taken up by the form, so that the action tends to draw the strip from the clamps, and, if this action is prevented, the clamps must be moved towards the form, otherwise the strip would be ruptured. Movement of the clamps towards the form is however permitted by movement of the slides 25, but this movement is controlled by the cams 32, the faces of which are so formed that only sufficient movement of the clamps longitudinally of the strip is permitted, to correspond to the extent to which the strip is taken up by the form, so that the strong tension which was placed on the strip initially will not in any degree be relaxed, and will at all times be sufficient to prevent any buckling of the strip, or wrinkling, gathering, or plaiting the sides thereof, which would otherwise occur, as the radius of curvature of the edges of the channel is somewhat shorter than that of the base portion thereof. This involves a certain elongation or stretching of the base portion of the channel, the metal of which it is formed having sufficient ductility to permit this action without rupturing it. The cams 32 will, therefore, be accurately designed to hold the strip under exactly the correct tension to produce the desired results, permitting the clamps to be moved towards the form only to the extent sufficient to prevent rupture.

At the end of the movement. the power will be automatically shutoff and at the same time, the rear rolls 30 will pass into the depressions 34 of the cam, permitting the clamps to move in a direction to relax the tension on the strip, so that, when the clamps are disengaged from the strip to remove it, the remaining tension on the strip will not cause any movement thereof between the clamp members which might'mar the finished surface of the strip. After the strip has been removed the parts will be returned to their initial positions.

The fixed members 26 of the clamps are preferably so formed that, at the end of the bendin operation, they will not only be held in alignment with the adjacent end portions of the form 12,

but willbe practically continuous therewith, as shown by the dotted line positions of Fig. 1, so that there will be no undesirable bending of the strip at this point.

In practice, where the strip is to be used in positions in which the side portions of the U-form bend will be parallel, the bending operation will preferably be carried to a point where these portions will be held in convergent relation, as shown in Fig. 6, as they may be then sprung apart to parallel relation and will tend to fit tightly against.

the parts with which they are engaged, when placed in position.-

It will be understood that, while the above described machine is primarily designed to form two sharp bends in the strip simultaneously, a single bend could be formed in a strip by having one of the clamps held stationary while the other was moved as abovedescribed.

I claim:

1. A machine for bending metal strips comprising a. form about which the strip is to be convoluted, a pair of clamps disposed oppositely with relation to said form and adapted for positive engagement with opposite portions of the strip, means for relatively moving one of said clamps and said form transversely of the strip to convolute the same about the form and longitudinally of the strip according to length thereof taken up by the form and a cam device for controlling the extent of said longitudinal movement, to maintain a predetermined tension on the strip during the convoluting operation.

2. A machine for bending metal strips comprising a form about which the strip is to be convoluted, a pair of clamps disposed oppositely with relation to said form and arranged for positive engagement with opposite portions of the strip,

one of said clamps being arranged for simultaneous movement longitudinally and transversely of the strip, to convolute the same about the form and a fixed cam arranged for engagement with said clamp to control the longitudinal movement thereof and maintain a predetermined tension on the strip during the convoluting operation.

3. A machine for bending metal strips comprising a form about which the strip is to be convoluted, a pair of clamps disposed oppositely with relation to said form and arranged for positive engagement with opposite portions of the strip, means to move said clamps simultaneously in directions transverse to the strip, to convolute the same about opposite portions of the form, and a pair of cams arranged to control the relative positions of said clamps longitudinally of the strip, to maintain the same under a predetermined tension during the transverse movement thereof and to permit movement of the clamps towards the form to correspond to the length of the strip taken up by the form.

4. A machine for bending metal strips comprising a form about which the strip is to be convoluted, a pair of clamps disposed oppositely with relation to said form and arranged for positive engagement with opposite portions of the strip,

means for moving said clamps relatively to place the strip under initial tension and for thereafter relatively moving one of said clamps and said form transversely of the strip, to convolute the same about the form and longitudinally of the strip according to the length thereof taken up by the form and a cam for positively controlling the extent of said longitudinal movement to mainly of the strip according to the length thereof taken up by the form and a fixed cam arranged to control the extent of said longitudinal movement in time with said transverse movement, to maintain a predetermined tension on the strip during the bending operation and to release said tension at the end of said operation.

DAVID C. BAILEY. 

